Peruvian Primrose (Ludwigia peruviana) Ecological Risk Screening Summary U.S. Fish & Wildlife Service, July 2015 Revised, March 2018 Web version, 8/17/2018 Photo: Forest & Kim Starr. Licensed under Creative Commons BY 3.0. Available: https://www.biolib.cz/en/image/id51350/. 1 Native Range and Status in the United States Native Range GISD (2018) lists Ludwigia peruviana as native in Argentina, Belize, Bolivia, Brazil, Cayman Islands, Chile, Colombia, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Haiti, Honduras, Jamaica, Mexico, Nicaragua, Panama, Paraguay, Peru, Trinidad and Tobago, Uruguay, and Venezuela. 1 Status in the United States GISD (2018) lists Ludwigia peruviana as alien, invasive, and established in Puerto Rico, Alabama, Florida, Georgia, North Carolina, Texas, and Washington. From GISD (2018): “In Washington L. peruviana has established in the drainage canals in the Longview/Kelso area. A new site was also recently discovered in King County (Washington State Department of Ecology, 2001).” “L. peruviana is being sold as an ornamental species because of its showy yellow flowers. Lake residents are strongly discouraged from planting water primrose in lakes, private ponds, in a flood zone, or in natural waterbodies. As of January 2001, these plants will no longer be offered for sale in Washington (Washington State Department of Ecology, 2001).” Clewell (1999) states that Ludwigia peruviana is an indigenous species in Florida. Means of Introductions in the United States No information on means of introduction for Ludwigia peruviana in the United States was found. Remarks There is some discrepancy as to the native or non-native status of Ludwigia peruviana in Florida (Clewell 1999; GISD 2018). 2 Biology and Ecology Taxonomic Hierarchy and Taxonomic Standing From ITIS (2018): “Taxonomic Status: Current Standing: accepted” “Kingdom Plantae Subkingdom Viridiplantae Infrakingdom Streptophyta Superdivision Embryophyta Division Tracheophyta Subdivision Spermatophytina Class Magnoliopsida Superorder Rosanae Order Myrtales Family Onagraceae Genus Ludwigia Species Ludwigia peruviana (L.) H. Hara” 2 Size, Weight, and Age Range From GISD (2018): “Ludwigia peruviana as is a perennial, sometimes deciduous, wetland shrub that can grow to 3 and 4 meters.” Environment No information on specific environmental requirements of Ludwigia peruviana was found. Climate/Range From Chandrasena (2005): “In Australia, infestations south of Sydney, in Sutherlandshire, latitude ≈30° South, are the southern-most limit of its current spread. The pantropical occurrence, across several continents, and tolerance of conditions from sea level to > 1450 m altitude […]” Distribution Outside the United States Native GISD (2018) lists Ludwigia peruviana as native in Argentina, Belize, Bolivia, Brazil, Cayman Islands, Chile, Colombia, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Haiti, Honduras, Jamaica, Mexico, Nicaragua, Panama, Paraguay, Peru, Trinidad and Tobago, Uruguay, and Venezuela. Introduced From Chandrasena (2005): “According to Raven (1963), introduced in the Old World, the species became naturalised in Asia, South India, Sri Lanka (Ceylon), Singapore, Northern Sumatra and Java.” GISD (2018) lists Ludwigia peruviana as alien, invasive, and established in Australia, Dominican Republic, Tahiti, India (including Andaman and Nicobar Islands), Indonesia, New Zealand (Canterbury Region), and Sri Lanka, and as alien and established in French Polynesia. Means of Introduction Outside the United States From Chandrasena (2005): “The history of its introduction in Sydney, first as a Botanical specimen, […]” “It is possible that L. peruviana infestations in Botany Wetlands, which existed for nearly 20 years, may have been the source of infestation of the weed for further spread in the Sydney basin. By late-1980s, infestations were found in Heathcote, about 40 km south of Sydney, and in Gosford, about 80 km north of Sydney (Jacobs et al 1993).” 3 Short Description From GISD (2018): “Ludwigia peruviana as is a perennial, sometimes deciduous, wetland shrub that can grow to 3 and 4 meters. It reproduces by seed and there are many small sand-like seeds in 4 to 5 rows within a capsule and can produce soil seed banks of 1 million seeds /m2. L. peruviana's stems are brownish green, heavily branched, and hairy when young. The leaves are alternate, rarely opposite, ovate, 5 to 10cm long, 1 to 3cm wide, and hairy. The solitary flowers are bright yellow and quite showy and bisexual, 2 to 4cm in diameter, but the 4 (-5) petals last for only a day. There are 4 pale green sepals that are typically 8 to 12mm long, and petals 1 to 3cm long and wide. L. peruviana's fruit is an erect capsule. The seed is light brown, subglobular, and 0.6 to 0.8mm long. The root system consists of a woody taproot with laterals close to the surface (PIER 2005; Sydney Olympic Park Authority 2004) and sometimes with white spongy vertical pneumatophores, especially in water.” Biology From Chandrasena (2005): “Mature L. peruviana stands in Botany Wetlands produced ≈ 450,000 seeds m-2 (Jacobs et al 1994). In addition, there were ≈ 65,000 seeds m-2 in the soil seed bank and ≈ 300,000 seeds m-2 in old fruits, which remained on stems over winter. Young plants flowered within two years. Within a year, there are two periods of flowering (spring and late summer) in Sydney. Seed viability was extremely high, in the range of 80-99% in the first year, declining significantly within 2 years (Jacobs et al 1993). The small seeds germinate readily in mud throughout spring and summer. There was some evidence of dormancy, possibly due to the hard-seed component of the seed bank, but this appears to break down after about one year (Jacobs et al 1993). The seeds of L. peruviana are hydrophobic, which make them germinate while afloat or underwater (Jacobs et al 1993). But the seedlings eventually float to the surface for establishment along shorelines, and also allow L. peruviana to form floating islands.” Human Uses From Dike et al. (2012): “The investigations revealed that a total of 22 species namely […], Ludwigia peruviana (L.) Hara., […], are used in the treatment of malaria in the south-western regions of Nigeria” Diseases No information on parasites or pathogens of Ludwigia peruviana was found. 4 Threat to Humans No information on threats to humans from Ludwigia peruviana was found. 3 Impacts of Introductions From Barua et al. (2017): “In the study area, where the wetlands (peatlands and stream beds) and ecotones (marshlands) were infested by primrose-willow [Ludwigia peruviana], there was major reduction in the size of indigenous plant community. It was more severe in the marshlands, where the weed attained a near climax state (Figure 8 [in source material]). Such a situation triggered not only the elimination of several resident plant species and increased vulnerability of several other habitat- sensitive plants, but also pose a threat to several animals (Table 5 [in source material]) and other organisms of the ecosystem. The extensive occurrence of primrose-willow has severely disturbed the normal food web of the threatened biota.” From Chandrasena (2005): “The main potential deleterious effect of both species [Ludwigia peruviana and L. longifolia] is their ability to supplant native species in wetlands and in riparian zones of waterways, which could result in permanent changes to flora, fauna and ecological diversity in such ecosystems. Dense stands of L. peruviana intercepted 93% of incident light (Jacobs et al. 1993), which led to dramatic losses of smaller native freshwater wetland plants and a reduction in bird populations. In the interconnected Botany Ponds, dense L. peruviana stands choked water flow between ponds and increased sedimentation. Reduced water flow increased the risk of flooding of adjacent properties. The addition of vast amounts of organic material, over decades, led to deoxygenation of ponds and wide ranging ecological damage. Recurrent toxic blue-green algal blooms were common in the ponds, which indicated, nutrient enrichment and a breakdown of natural food webs. These adverse changes threatened cultural, social, aesthetic and economic values of the Botany Wetlands (Chandrasena and Sim 1998). Negative social impacts included reduced opportunity for recreational use by the public.” From Chandrasena et al. (2002): “The potential of Ludwigia peruviana, a non-native plant, to become a significant aquatic weed in Australia has been apparent since 1971, when established populations were discovered in the Botany Wetlands in Sydney. In the 1990s, dense L. peruviana infestations extended deeply into the ponds covering an estimated 40% of the wetland area, aggressively choking out most other native species (GHD, 1993, Jacobs et al. 1995). Declared under the Noxious Weeds Act (1993) as a W2 category noxious weed, L. peruviana requires to be “.…fully and continuously suppressed and destroyed…..” by the landowner.” 5 From GISD (2018): “L. peruviana is included in the First Schedule of the National Pest Plant Accord. All plants on the list are designated as Unwanted Organisms, and are banned from sale, propagation and distribution throughout New Zealand.” 4 Global Distribution Figure 1. Known global distribution of Ludwigia peruviana. Locations are in North and South America, southern Asia, and Australia. Map from GBIF Secretariat (2018). Figure 2. Known distribution of Ludwigia peruviana in India. Map adapted from India Biodiversity Portal (No date). 6 Additional known locations were